Build documentation for travis builds
Build documentation for travis builds

Problem:
travis builds are not building documentation.

Solution:
Added missing step in the travis file to build docs.

ryan-talley/cf-bigip-ctlr,dramich/cf-bigip-ctlr,dramich/cf-bigip-ctlr,ryan-talley/cf-bigip-ctlr,dramich/cf-bigip-ctlr,dramich/cf-bigip-ctlr,ryan-talley/cf-bigip-ctlr,ryan-talley/cf-bigip-ctlr